The present invention relates to interchangeable objectives for cameras of the type having an objective tube and a lens mounting axially displaceable thereon so that the diaphragm may be adjusted after the objective has been inserted.
Objectives for cameras of the type referred to above are known. These known objectives are focussed by axial displacement of the lens in the objective tube. A knurled ring is arranged at the objective tube for turning, and a worm gear translates the turning motion into an axial displacement of the lens mounting in the objective tube. The objective may be focussed and the diaphragm may be adjusted, e.g. by means of a diaphragm adjustment ring, even when the objective has been removed from the camera. Also, the objective tube carrying the lens with the diaphragm, the knurled ring and the diaphragm adjustment ring may be moved at will within the bayonet ring of the objective regardless of whether the objective is mounted at the camera bayonet mounting or not.
Cameras are known having an exposure metering or exposure control system which require coupling with the objective diaphragm. In this case, it is conventional practice to provide the diaphragm adjustment ring with a plunger extending from the objective in direction to the camera or with a pin which can be swivelled. Such a plunger or pin engage a coupling element in the camera to couple the diaphragm with the exposure metering or control system when the objective is introduced and locked to the camera. The coupling must be coordinated with the introduction or removal of the objective that the coupling elements and plungers or pins clearly cooperate in a form-locking and positive-drive position.